Crane with twin motor winch



July'2, 1968 w. J. LADO ETAL 3,390,785

CRANE WITH TWIN MOTOR WINCH Filed April 18, 1966 2 Sheets-Sheet 1 D D DD a W/Zt/AM 1/. 440a United. States Patent 3,390,785 CRANE WITH TWINMOTOR WINCH William J. Lado, Rome, N.Y., and Wilhurn Kelly Brown, MortonGrove, IlL, assignors to Pettibone Mulliken Corporation, a corporationof Delaware Filed Apr. 18, 1966, Ser. No. 543,390 6 Claims. (Cl. 212-35)ABSTRACT OF THE DISCLGSURE A crane winch is driven through two identicalhydraulic motors, one at each end of the winch shaft. Each drives theshaft through a worm gear. The motors can be connected hydraulically inseries or in parallel to provide two winch speeds and two winch torques.If the hydraulic source includes two pumps of different capacities andseparate control valves, the number of speeds with constant pump speedis increased to six.

This application, the disclosure of which is offer d for publicdissemination in the event that adequate patent protection can begranted, relates to hydraulic cranes, and particularly to twin hydraulicwinches on such cranes.

Although some cranes may have uniform loads time after time, mobilecranes tend to be used for a very wide variety of loads. A mobile cranerated at tons of lifting capacity may only rarely have to lift anythingthat heavy. The rest of the time, its load may vary all of the way downto 100 pounds, or even ten. However, the motor means for driving itswinch must be capable of exerting on the line the force necessary forraising the rated load. In the past, the practical ways of achieving theneeded force or winch-torque with hydraulic winches have meant that theline speed must be rather low.

Of course, it has been possible to accomplish some adapting of theequipment by using multipart hooks which included block and tacklearrangements so that the load might weigh for example six times the linetension. However, a six part line reduces the load speed to one sixth ofthe line speed, and conversion to provide full line speed is not easyenough to justify the change every time the load weight changes.

One crane manufacturer has provided three line speeds by using two pumpsof different capacity each controlled by a separate valve, with themaximum winch speed being attained by opening both valves. However,utilization of the slowest of the three speeds was not accompanied byany increase of line tension, because with all three speeds a maximumline tension was determined by the same maximum hydraulic pressure.Likewise, reducing the speeds still further by merely cracking open thevalve does not add any line tension. There has long been a recognizedneed for the ability to increase the line tension beyond that at whichit would be operating the great majority of the time. A speed reductionwith the increased line tension is tolerable and often desirable.

To increase the line tension by providing even larger hydraulic motorsor by further gear reduction between the motors and the winches, andcorrespondingly increased pump sizes to maintain speed for light loadswas a recognized possibility but not a satisfactory solution of theproblem because of the great cost of such equipment, the space it wouldrequire, and the power loss represented by pumping for lighter loads thesame oil which would have been required for maximum loads.

According to the present invention one step in the solution of theproblem is in providing two hydraulic Winch motors, each of which may beidentical to the single "ice - draulically in parallel. With seriesconnection, the winch will function in the same manner as heretoforewith one hydraulic motor of the same size as one of the twin motors nowprovided. But for the exceptionally heavy loads, a shift of the valve toproduce parallel connection will not only reduce all of the speeds tohalf their previous speeds, but will double the winch-torque, or theavailable line tension.

Nearly all of the parts would be identical to parts already made andstocked (both for manufacture and for repair) for cranes with thepresent single winch motors.

Additional objects and advantages will be apparent from the followingdescription and from the drawings.

Designation of figures FIGURE 1 is a perspective view of a hydrauliccrane for which the present invention is highly suitable;

FIGURE 2 is a transverse view partly broken back to an axial section ofthe winch. It is basically on the line 22 of FIGURE 3, but a portionthereof is on the line 2'2' of FIGURE 3;

FIGURE 3 is a side view of the structure shown in FIGURES 1 and 2;

FIGURE 4 is a hydraulic diagram of the preferred embodiment, and

FIGURE 5 is a fragmentary view similar to part of FIG. 4, but showingthe two motors connected in parallel, as distinguished from the seriesconnection of FIG. 4.

General description Although the. following disclosure offered forpublic dissemination is detailed to ensure adequacy and aidunderstanding, this is not intended to prejudice that purpose of apatent which is to cover each new inventive concept therein no matterhow others may later disguise it by variations in form or additions orfurther improvements. The claims at the end hereof are intended as thechief aid toward this purpose; as it is these that meet the requirementof pointing out the parts, improvements, or combinations in which theinventive concepts are found.

Although the present invention is largely independent of the form ofcrane on which it is used, it perhaps finds its greatest utility inconnection with heavy duty mobile cranes, such as shown in FIGURE 1.Such a crane may be provided with a chasis 11 running on tires 12.Preferably there are outrigger feet 13 which can be hydraulicallylowered to provide firm and widespread support for heavy duty craneoperations. A turntable carries a pedestal 16 to which a main boom orshipper 17 is pivoted, to be raised and lowered by hydraulic control ofa pair of cylinders 18 of which one is shown. One or more boomextensions 19 may be provided and they can preferably be hydraulicallyextended to provide a desired boom height when the boom is elevated. Aboom head 21 is provided with a sheave, not shown, from which a cable 22extends downwardly to a hook 23. In the illustrated form, the hook 23 iscarried by a block 24 and hence there would be a multinart line, anadditional part being the upwardly extending run 26. The cable 22extends rearwardly from its sheave to a winch assembly 27 which isdriven through worm gear assembly 32, by a hydraulic motor 28 to pay outor draw in the cable.

According to the present invention, the drum 31 of the winch is providedwith two hydraulic motors 28 and 28 (FIG. 4). FIGURE 2 shows the twoworm gear assemblies 32 and 32' which would be driven by the two motors,and each of which is coupled to one end of the winch drum. In a sense,each motor is represented in FIG. 2 by the coupler 33 or 33' whichcouples the hydraulic motor to the respective worn shaft 34 or 34.

As seen in FIGURE 4 and FIGURE 5, the two motors 28 and 28 .areconnected in series, with the FIGURE 4 position of a series-parallelvalve 36; and in parallel, with the FIGURE position of the same valve36. Although this valve may be controlled by direct manual operation,there are many situations in which it should be remotely controlled. Insuch instances, it may be controlled hydraulically by a manual valve 37.In one position, the valve 37 can connect pressure oil to one end of thevalve 36 to shift its spool 83 as seen in FIGURE 5, while in the otherposition it can connect the same end of the valve to drain (back to thereservoir) so that the spool will be pressed to the FIGURE 4 position bya spring 38. The valve 37 may have a handle 39. Regardless of theposition in which the valve 37 has been placed, the raising and loweringoperations will be controlled by valve levers 41 and 42. These arepreferably accessible from the drivers seat of the vehicle, and wheneither or both are pulled rearwardly, the winch will be driven in adirection to raise the load. When either or both of the handles or valvelevers 41, 42 is pushed forwardly from a neutral position, the winchwill be driven in a direction to lower the load. With the handles inneutral position, the winch motors will be hydraulically locked and theload will be safely held.

Winch construction In many respects the winch is identical withhydraulic winches which have been used heretofore. In fact, thehydraulic motor 28 and the worm gear assembly 32, as well as theirconnecting portions, are preferably identical with those which have beenused heretofore when the drum 31 was driven by a single hydraulic motor.Thus the worm on worm shaft 34 has heretofore driven a worm wheel 46which drove a shaft 47 by which at least one end of the drum 31 wascarried, and the drum driven. All of the drive structure is nowsubstantially duplicated at the opposite end of the drum 31. So far aspossible, the parts are identical, to provide a minimum number ofmanufacturing and replacement parts.

Instead of having one shaft extend through the drum 31, the shafts 47and 47 have their respective ends 48 and 48 projecting into the drumfrom opposite ends thereof, each being splined or keyed to the drum.With the gear housing covers 49 and 49' removed, and with the wormshafts removed, the assembly at each end can be removed. Thus, the shaft47, together with its bearings, and worn wheel 46 may all be slipped outaxially. When the same thing is done at the other end, the drum may beinserted or removed.

There is preferably provided a guide roller 51 for the cable asheretofore. It runs in bearing housings 52, which are preferably carriedby leaf springs 53, and rest on surfaces 54 of the side plates 56 of thewinch drum housing. This mounting permits the roller to yield upwardlyif the winding of the cable on the drum should so require.

Hydraulic circuit The preferred form of circuit is shown in FIGURE 4.Two pumps 61 and 62, having different pumping capacities, but pumping atthe same pressure, are both driven by the engine of the crane vehicle.Each is provided with a relief valve 63, the settings of which will bethe same. Each is provided with a manual valve 64 or 64, the valve 64being controlled by the handle 41 and the valve 64' being controlled bythe handle 42. If either or both valves are operated in the liftdirection, pressure oil drawn by pump 61 or pump 62, or both, from thereservoir will be supplied through line 66 to the winch motors 28 and28'.

From the line 66 it will reach these winch motors by flowing freelythrough a check valve portion 67 of an anti-cavitation valve assembly68, and thence to valve 36. With valve 36 in the FIGURE 4 or seriesposition, the oil will flow through ports 69 and 69 to motor 28, andafter driving the motor 28 Will flow through ports 71 and 72 to motor28' from which it will return by line 73 to valves 64, 64 and fromeachof these that has been actuated to the reservoir. For lowering, one orboth of the handles 41, 42 will be drawn rearwardly shifting the coresof valves 64, 64 in the opposite direction from their midposition, andoil will be supplied through line 73 following exactly the reversecourse of that just described, except in the anticaviation valve 68.Here the check valve 67 prevents flow through it of the oil in theload-lowering direction. Pilot valve section 76, when at rest, is biasedby spring 77 to a position at which it prevents any flow of oil throughthis section of the valve. However, when pressure oil is supplied toline 73, a connection 78 carries this oil to the pilot aperature ofpilot valve 76 where it overcomes the strength of spring 77 and shiftsthis valve to open it to the flow of oil through this section of thevalve, whereupon the oil can flow from the hydraulic motors 28 and 28'through pilot valve 76 and line 66 and valves 64, 64 to the reservoir.

With the valves 64, 64' in their mid or neutral or locked position, themotors 28, 28 can not turn. The weight of the load is unable to causethe motors to turn or even to keep on turning if they had been turningin a load-lowering direction because as soon as pressure oil ceases tobe supplied to connection 78, spring 77 shifts the pilotactuated valve76 to its closed position.

If an exceptionally heavy load is to be raised so that double the forceis desired, or if for some other reason, only half of the lowest speedis desired, the hydraulic actuation is the same except for the changesindicated in FIGURE 5. In this figure, valve handle 39 has been turnedto the low-speed position connecting oil pressure line 81 with line 82to the end or pilot port of seriesparallel valve 36 forcing its spool 83to the position shown in FIGURE 5, thereby compressing spring 38. Withthe spool 83 in this position, oil entering port 69 can flow both toport 69' (through motor 28) and to port 72 (through motor 28'). The oilreturning to valve 36 from motor 28 still enters valve 36 at port 71,but now flows out through port 84 directly to return line 73.

When the extra line tension or extra slow speed is no longer desired,handle 39 is shifted to the high-speed position and valve 37, as seen'in FIGURE 4, connects line 82 to the reservoir to permit oil to flow outfrom the pilot aperture of valve 36 under the influence of spring 38,Which shifts the spool 83 to the position shown in FIGURE 4.

Six speeds available With this arrangement, six line speeds areavailable with fully open valves. Half of these speeds have doubletorque. The speeds available are related to each other as follows, thespeeds underlined being at double torque: 2; 4; 6 and 10.

It may be a little surprising that with both hydraulic motors working onthe drum all of the time, there is any more torque available withparallel connection than with series connection. The reason is that theoil cannot exert the force represented by its maximum pressure on bothof the motors when they are connected in series, but it can when theyare connected in parallel. When they are connected in series, if thefull hydraulic force is utilized on turning the first motor, to whichthe oil is supplied, there will be none left for turning the secondmotor. As a matter of fact, the two motors will inherently accomplishautomatic distribution of their use of oil pressure so that there willnecessarily be at least enough pressure supplied to the second motor tokeep it turning. If the first motor does substantially all of the workduring the series connected condition, the action and the wear will besubstantially the same as if only one motor were provided. There may,however, be some tendency for the two motors to share the load, in whichcase the parts will work at about half the frictional contact pressureas would be present if only one motor were provided, and hence the wearmay be greatly reduced.

Although six speeds can be made available as noted, economy may dictateusing a single main manual control valve. The two speeds then providedby the present invention (and the ability to increase winch tongue forexceptionally heavy loads) will be a tremendous im provement over thesingle speed by which most hydraulic cranes 'have been characterized.

We claim:

1. A mobile crane including a powered mobile chassis, and hydrauliccrane mechanism thereon having a boom swingable about a vertical axisand liftable about a horizontal axis, and hydraulic winch meansassociated with the boom, and including a drum, a line wound on saiddrum and extending down from the boom for raising a load when drawn inby said winch;

said winch including a pair of separate substantially identicalhydraulic winch motors connected by substantially identical worm driveassemblies in driving relationship to said drum, said hydraulic motorsbeing substantially identical to one another;

and a hydraulic circuit for driving said hydraulic winch motorsincluding a reservoir, relief-valved pump means drawing fluid from thereservoir, a return line discharging to the reservoir and winch poweringlines leading to ports on the winch motors, and manually controlledvalve means for connecting the pump means and return line to saidpowering lines in either direction and for closing them against flow, aseries-parallel valve for at will connecting said two hydraulic motorsin series or in parallel in their connection to said powering lines whenincreased torque or reduced open-valve speed is desired.

2. A hydraulic crane having a boom liftable about a horizontal axis, andhydraulic winch means associated with the boom, and including a drum, aline wound on said drum and extending down from the boom for raising aload when drawn in by said winch;

said winch including a pair of separate substantially identicalhydraulic winch motors connected by substantially identical worm driveassemblies in driving relationship to said drum, said hydraulic motorsbeing substantially identical to one another;

and a hydraulic circuit for driving said hydraulic winch motorsincluding a reservoir, relief-valved pump means drawing fluid from thereservoir, a return line discharging to the reservoir and winch poweringlines leading to ports on the winch motors, and manually controlledvalve means for connecting the pump means and return line to saidpowering lines in either direction and for closing them against flow, aseries-parallel valve for at will connecting said two hydraulic motorsin series or in parallel in their connection to said powering lines whenincreased torque or reduced open-valve speed is desired.

3. A hydraulic crane according to claim 2, in which the pump means is apair of different capacity pumps, and the manually controlled valvemeans includes a pair of valves each connected to one of the pumps,these valves being operable at will singly or jointly to provide threehydraulic flow rates, in turn providing six winch speeds at twodifferent winch torques upon selective operation of the series-parallelvalve.

4. A mobile crane including a powered mobile chassis, and hydrauliccrane mechanism thereon having a boom swingable about a vertical axisand liftable about a horizontal axis, and hydraulic winch meansassociated with the boom, and including a drum, a line wound on saiddrum and extending down from the boom for raising a load when drawn inby said winch;

said winch including a pair of separate substantially identicalhydraulic winch motors connected by substantially identical worm driveassemblies in driving relationship to said drum, said hydraulic motorsbeing substantially identical to one another;

and a hydraulic circuit for drivingsaid hydraulic winch motors includinga reservoir, pump means drawing fluid from the reservoir, a return linedischarging to the reservoir and winch powering lines leading to portson the winch motors, and manually controlled valve means for connectingthe pump means and return line to said powering lines in eitherdirection and for closing them against flow, a seriesparallel valve forat will connecting said two bydraulic motors in series or in parallel intheir connection to said powering lines when increased torque or reducedopen-valve speed is desired; said circuit including an anticavitationvalve means for preventing flow from said motors in the load loweringdirection except when there is a positive fluid pressure connected torotate them in that direction; the pump means including a pair ofdifferent capacity pumps, and the manually controlled valve meansincluding a pair of valves each connected to one of the pumps, thesevalves being operable at will singly or jointly to provide threehydraulic flow rates, in turn providing six winch speeds at twodifferent winch torques upon selective operation of the seriesparallelvalve.

5. A hydraulic crane having a boom liftable about a horizontal axis, andhydraulic winch means associated with the boom, and including a drum, aline wound on said drum and extending down from the boom for raising aload when drawn in by said winch;

said Winch including a pair of separate substantially identicalhydraulic winch motors connected by substantially identical worm driveassemblies in driving relationship to said drum, said hydraulic motorsbeing substantially identical to one another;

and a hydraulic circuit for driving said hydraulic winch motorsincluding a reservoir, relief-valved pump means drawing fluid from thereservoir, a return line discharging to the reservoir and winch poweringlines leading to ports on the winch motors, and manually controlledvalve means for connecting the pump means and return line to saidpowering lines in either direction and for closing them against flow, aseries-parallel valve for at will connecting said two hydraulic motorsin series or in parallel in their connection to said powering lines whenincreased torque or reduced open-valve speed is desired; said circuitincluding an anticavitation valve means for preventing flow from saidmotors in the load lowering direction except when there is a positivefluid pressure connected to rotate them in that direction; the pumpmeans including a pair of different capacity pumps, and the manuallycontrolled valve means including a pair of valves each connected to oneof the pumps, these valves being operable at will singly or jointly toprovide three hydraulic flow rates, in turn providing six winch speedsat two difterent winch torques upon selective operation of theseries-parallel valve.

6. A hydraulic crane having a boom liftable about a horizontal axis, andhydraulic winch means associated with the boom, and including a drum, aline wound on said drum and extending down from the boom for raising aload when drawn in by said winch;

said winch including a pair of separate substantially identicalhydraulic winch motors connected by substantially identical worm driveassemblies in driving relationship to said drum, said hydraulic motorsbeing substantially identical to one another;

7 8 anticavitation' valve means'fo'r preventing flow from ReferencesCited said motors in the" load 'lowering'direction except V UNITED ST1'; ATENTS when there is a positive fluid pressure connected torotatethem in that direction; 6471239 4/1900 P v f and a hydrauliccircuit fordriving said hydraulic-Winch 5 2638375 5/1953 "Bowdltch'et 9129 motors including a reservoir, relief-valved pump 2,903,852 9/1959meansdrawing fluid from the reservoir," a return 2,953,903 9/1960 Skoogat linedischarging to the reservoir and winch power- 3,045,836 7/1962Evans ing lines leading to ports on the winch motors, and 3,161,02212/1964 6O3'3 manually controlled valve 'means for connecting 103,249,336 5/1966 Brown et 254"186 X 'the pump means and return line tosaid powering lines in either direction and for closing them against 1'flow, a series-parallel valve for at Will connecting g 'igi said twohydraulic motors in series or in parallel i in their connection to saidpowering lines When in- 15 EVON c 'EL lim er creased torque or reducedopen-valve speed is desired. M. L. AJEMAN, Assistant Examiner.-

FOREIGN PATENTS" v

